This invention relates to an improved fermentation process for producing angiotensin I converting enzyme inhibitor A-58365 factor B. In particular, it relates to an improved fermentation process for producing A-58365 factor B which comprises culturing Streptomyces chromofuscus NRRL 15098 under submerged aerobic fermentation conditions in an aqueous nutrient culture medium supplemented with the amino acids proline and lysine.
The angiotensin I converting enzyme inhibitors A-58365 factors A, B, and C and the process for the production thereof are described in copending application Ser. No. 409,763 filed this even date (attorney docket No. X-5950). A-58365 factor A is the major factor, i.e. most abundant, produced in the fermentation of S. chromofuscus NRRL 15098, while factors B and C are produced in minor amounts in relation to factor A. In copending application Ser. No. 409,765 filed this even date there is described an improved process for producing A-58365 factor A in greater abundance which comprises culturing the S. chromofuscus strain in an aqueous nutrient culture medium containing between about 1 g and about 6 g of proline per liter of culture medium. According to the process of the present invention, when between about 1 g and about 3 g of lysine is added to the proline containing culture medium for S. chromofuscus the fermentation provides surprisingly enhanced yields of A-58365 factor B with factor B now being produced in greater abundance than factor A.